The National Heart, Lung and Blood Institute says 1.2 million Americans have a heart attack each year. So, how much do you know about heart attacks?

What happens during a heart attackYour heart is a muscle. Its job is to pump blood to and from the lungs and your many body parts. The lungs take carbon dioxide from your blood and put in oxygen. Your heart moves this oxygen-rich blood to your muscles and other organs. Blood returns to the heart filled with carbon dioxide. It again pumps through the lungs, and the process repeats.

Since it's a muscle, your heart needs oxygen, too. Coronary arteries, which are blood vessels that bring blood to the heart, fulfill this job. But like other blood vessels, coronary arteries can get clogged. Buildup of fat, cholesterol and other material, known as plaque, can make artery walls thicker and harder. This is the most common reason for a heart attack. Sometimes the plaque tears. The body reacts by forming a blood clot around the tear. This may completely block the artery so no blood gets through.

If parts of the heart go too long without oxygen-rich blood, the muscle tissue can die. This damage or death of heart tissue is called a heart attack, or myocardial infarction.

When should I go to the hospital if I have chest pain?
If you think you or someone else is having a heart attack, call 911 immediately! Minutes count during a heart attack. Emergency medical personnel can assess your situation and begin treatment right away. Do not drive or have someone drive you to the hospital.

You might not be sure that what you're feeling is a heart attack. Sometimes symptoms aren't obvious or come on slowly. Chances are it won't be anything like what you've seen in the movies. Even so, call 911 right away. Heart attacks kill thousands each year. Many of those people die within an hour of noticing symptoms.

You likely know that chest pain is a warning sign, but do you know the other symptoms? A 2005 survey found only 27 percent of people knew all the major symptoms. And most didn't know to call 911 right away!

Symptoms of a heart attack can include:

Chest pain or discomfort. This includes feelings of pressure, tightness, heaviness or squeezing. It may last more than a minute or come and go. This is the most common sign in both men and women.

Pain or discomfort in the upper body. It might be in the throat, jaw, back, neck, shoulders, stomach or arms.

Shortness of breath. This may happen with or without chest discomfort.

Nausea, vomiting, indigestion, light-headedness, sudden dizziness or breaking out in a cold sweat.

Fatigue or trouble sleeping.

While chest pain is the most common symptom for both men and women, it's important to note that women are more likely than men to have some of the other warning symptoms. Women may notice chest discomfort - pressure or tightness - or no pain at all. Women are more likely to feel short of breath, nauseated or fatigued. They may also vomit, feel dizzy or have back or jaw pain. They are less likely than men to feel severe chest pain.

In one study, a third of patients who had heart attacks had no chest pain. They were more likely to be older, female or have diabetes. People with diabetes may not have any symptoms or very mild symptoms.

Remember, if you notice symptoms of a heart attack or believe you or someone else is having a heart attack, call 911 right away.

By Emily A. King, Contributing WriterCreated on 06/09/1999Updated on 01/14/2013

Sources:

National Heart, Lung and Blood Institute. Heart attack: Know the symptoms. Take action.

National Heart, Lung and Blood Institute. What is a heart attack?

Centers for Disease Control and Prevention. Heart disease facts.

National Heart, Lung and Blood Institute. What are the signs and symptoms of a heart attack?